the big funky E is the summation operator where you just add elements of an array together
the ~ means approximately equal to (i.e trying to assign a value to an irrational number)
the small e is the only number (rational or irrational, e is irrational) where the derivative of e^x is e^x (I think that's how it goes)

e is:
2.718281828459045235360287471352662497757247093699 95957

and those are the first 3 relevant symbols I could think of that might be in your book

"...the results are undefined, and we all know what "undefined" means: it means it works during development, it works during testing, and it blows up in your most important customers' faces." --Scott Meyers